Air conditioning apparatus



Jul 14, 1936. c. A, RODMAN AIR CONDITIONING APPARATUS s Sheets-Sheet 1Filed Aug. 26, 1933 July 14, 1936'. c, A, R A 2,047,799

AIR CONDITIONING APPARATUS Fild Aug: 26, 1933 5 Sheets-Shet 2 July 14,1936. WA 2,047,799

AIR CONDITIONING APPARATUS Y 1 Filed Aug. 26, 1933 '3 Sheets-Sheet 3 -56Fl/vs .025 TH/VCK F/NS .006 TH/CA 36 I ELECTRIC CLOCK n/ .Z'U

v ,I I. 50

45 I 49 Jnven/ior' wee/5s: 66611767206 lied/7M0,

$21M z-r r Patented July 14,1936

Clarence A. Rodman,

AIR CONDITIONING APPARATUS PATENT OFFlCE Fort Wayne, Ind., assignor toJustin W. Macklin, Cleveland, Ohio, trustee Application August 26, 1933,Serial No. 687,070

10 Claims.

My invention relates to improvements in air conditioning apparatus andmethods of operating the same.

One object of the invention is to provide means for controlling the flowof refrigerant to the evaporator or expansion coil in such manner as tocause the latter to operate at or near the dew point without causingprecipitation of moisture on the surfaces of said evaporator orexpansion coil.

A contributory object is to cause the flow of refrigerant to take placeintermittently or in impulses andprovide means for positivelycontrolling the length of time that the expansion valve is opened andclosed.

Another objectis to provide, an improved valve for accomplishing theforegoing results, said valve having one part operated electrically, atpredetermined time intervals, and another part under thermal control.

Another object is to provide a valve in which the orifice isautomatically changed to compensate for variations in the load impressedupon the evaporator.

A further object is to provide equipment of this character which may beadjusted to maintain the air in humid condition or to dehydrate the air,as

may be desired.

An additional object is to provide equipment of this character in whichthe valve may be used in inverse refrigeration for heating purposes.

In the accompanying drawings I have illustrated one embodiment of theinvention which will serve to illustrate its advantages. V

Fig. 1 is a top plan viewof' the mechanism mounted in a suitablecontainer but with the top removed;

Fig. 2 is an elevation thereof with part of the side removed;

Fig. 3 is an end elevation with part of the end wall removed;

Fig. 4 is a section on the line 4-4 of Fig. 2 showing the evaporator;

Fig. 5 is an end view thereof;

Fig. 6 is a plan view of part of one of the evaporator coils;

Fig. 7 is a section thereof;

Fig. 8 is a plan view of part of a modified construction of evaporatorcoil;

\ Fig. 9 is a section thereof; and

.Fig. 10 is a sectional elevation of pansion valve. I

The mechanism is mounted on a suitable base l0 which may form part of ahousing having side walls ii and a top H. The compressor unitmay a formof exbe of any suitable construction and may comprise a motor I3 havinga belt drive l4 for operating the compressor [5. The motor shaft has afan It thereon. Beneath the motor is a tank I! which contains therefrigerant, which latter 5 may be methyl chloride,dichlorodifluormethene, or any other well known or suitable compound.

' Tracing first the flow of the refrigerant, the same passes from thereceiver tank I! through an outlet l 8 and a pipe I9 to a suitableexpansion 10 valve 20. This valve, as hereinafter pointed out, operatesto deliver the refrigerant intermittently, in impulses which may beadjusted as to their rapidity and duration. It may be any suitable valvestructure, intermittently operated by proper l5 mechanism, but ispreferably of special design and of the form shown in Fig. 8, andoperated by an electric clock, as hereinafter explained more fully. Fromthe expansion valve the refrigerant passes through a pipe 2 IV and isexpanded into the evaporator 22, which may be conveniently located inany desired relation with reference to the compressor and othermechanism. In the form shown in the-drawings it is located in acompartment below the one in which the com- 2 pressor is located. It isunderstood of course, that the air to be cooled is passed through theevaporator compartment around or through the evaporator coils and fins,as will be hereinafter explained. From the evaporator the refrigerant 30is returned through pipe 23 to the inlet 24 of the compressor l5 andafter being compressed is discharged through the outlet 25 and pipe 26to the condenser 21 where the heat is removed in the usual way and theliquid refrigerant is returned 35 throughpipe 28 to the tank l1.

The evaporator will now be described. The airto be cooled is drawn intothe evaporator chamber through an opening 30, along one of the sidewalls ll, near the bottom of the structure and follows a. circuitouscourse, horizontally to the other end of the housing and then back andforth at successively higher levels through 4 superimposed horizontalchambers formed by horizontal partitions 3| and 32, arranged instaggered relation and each extending from one end of the housing almostto the other end thereof, as shown in Fig. 2. During this back and forthflow, heat is extracted from the air by the evaporator fins and coilsand the cooled air is then drawn upwardly through the outlet 33 to theinlet side of the blower 30, and, passing through the rotor of theblower, is discharged from the outlet 35, shown as an opening in thecover i2. Where the structure is installed in an ornamental cabinet, thecooled air may of course be discharged into the room through horizontallouvers in a horizontal direction or in any desired direction.

A preferred form of expansion valve shown in Fig. 8 will now bedescribed. Another form of expansion valve is shown, described andclaimed in my co-pending application filed May 31, 1935, Serial No.24,381. Said valve may be called an electro-thermal expansion valve andit provides means for controlling the fiow of refrigerant through theevaporator or expansion coils so as to permit the operation of thelatter at or near the dew point without causing the precipitation justedto cause dehydration of the air passing through said evaporator byprecipitating the moisture on the surface of the evaporator. The

valve housing contains two valves, the first of which is opened and shutintermittently and the second of which remains open for a considerableinterval of time, although the effective size of the opening is variedin accordance with conditions. The relative arrangement of said twovalves may be reversed, however, i. c. with the electrically operatedvalve located between the thermal valve and the evaporator. The chamberof the electrically operated valve, through which the gas flows, has aport or seat from which the valve stem 36 may be lifted by the core atof a solenoid coil 38 when the latter is energized. The upper part ofthe structure is formed as a dash pot 39 having a spring 40 resistingsaid upward movement and serving to hold the valve on its seat when thecoilis deenergized. Said coil may be actuated by any suitable source ofelectric impulses such as a Telechron timer M, which is adjustable so asto regulate the opening and closing of the valve for any predeterminedlengths of time and at any desired intervals, thus causing therefrigerant to be released in impulses which may be long or short, asdesired. The remainder of the valve is designed to release the properamount of refrigerant to the evaporator or expansion coils in accordancewith the load impressed on the same. From the electrically controlledvalve the refrigerant flows through the passage 42 and through anopening in the valve seat 43, the stem of the valve M being normallypressed toward its seatby a spring t5, the tension of which may beadjusted. The valve stem is mounted in a suitable bracket 46 whereby itmay be moved away from its valve seat by a rod 41 under the influence ofa Sylphon 48 constituting the power element of the thermostatic part ofthe valve and which may be filled with the same refrigerant as is usedin the rest of the system.

The rod 4'! is surrounded by an additional bellows or Sylphon 49 toprevent leakage through the opening through which the rod 4! slides. TheSylphon '48 is connected by a suitable tube 50 to the outlet pipe fromthe evaporator, as hereinafter explained.

The refrigerant, after leaving the expansion valve in a short impulse,travels downwardly through tube 5| and then horizontally across theevaporator through a transverse tube 52 t0 the first return berid 53 andthen back through another transverse tube 52, preferably parallel to thefirst one, and then through another return bend 53 and so on back andforth through the entire series of parallel tubes in 'the lower one ofthree layers of such tubes. From the lower layer the flow continues backand forth through a second and similar layer above the first layer andsoon through successive superimposed layers; In the form illustratedthere are three such layers, the outlet end of the pipe being indicatedat 54. Surrounding said outlet end or otherwise closely associated withit is a closed container 55 containing the same refrigerant used in therest of the system, said container having the tube 50 connected theretowhereby the variations in temperature'of said container are communicatedto the sylphon 48 of the valve previously described in the form of avariable pressure which actuates said Sylphon.

The transverse tubes 52, 52', 52" are supported in the parallel metalwalls 56 passing through openings therein with the connecting bends 53outside of the enclosure formed by said walls. These bends aresurrounded by suitable insulating material 5'! whereby they arecompletely insulated from the relatively warm stream of air flowingthrough said evaporator.- Consequently said bends have a lowertemperature than the rest of the evaporator. As a result, therefrigerant fiowing through the condenser pipe is condensed somewhat inthese bends. For example, the first quantity of refrigerant gas releasedby the valve condenses in part in the first bend at the end of tube 52.Immediately thereafter a new charge or impulse of refrigerant isdischarged into said tube 52 which picks up in part the small amount ofcondensate left in the first bend 53. This process of partialcondensation and reevaporation in the bends repeats itself throughoutall of the transverse tubes in each of the three layers of tubing in theevaporator.

The pressure of these conflicting impulses may be varied within desiredlimits and maybe changed over the entire range of the possible operatingfield of the machine, according to the temperature desired foroperation. The time intervals of said impulses are in accordance withthe setting of the valve, which is electrically controlled.

Considering the various tubes 52, 52, 52", etc., during any particularimpulse the tubes are alternately cooler and warmer throughout theevaporator and on the succeeding charge they are the reverse.

Said tubes 52 are also provided with fins 58 made of good heatconducting material, preferably strips of metal, which are long enoughto extend throughout the entire length of the evaporator, each striphaving a series of openings therein through which the heat conductingtubes 52 pass. These strips, arranged vertically and in spaced parallelrelation, are shown in Fig. 4. The thickness of the fins has animportant bearing on the function performed by the apparatus. In Figs. 6and '7, for example, said fins may be assumed to have a thickness of.025 inch which is thick enough to result in a substantial transfer 'ofheat from one of the tubes 52 to its adjacent parallel tube. The tubesthemselves may be assumed to be inch copper tubes spacedthree inchesapart. In other words, the temperature of each tube is aifected by thetemperature of the preceding tube and the temperature of the succeedingtube, 1. e. the transfer of heat may be said to balance off. This isintended to be illustrated by the dotted line circles in Fig. 7.

If the thickness of the fins is substantially less,

as for example .008 inch, as indicated in Fig. 8

where also inch coppertubes are intended to 75:

be shown, but spaced inches apart, there is substantially no transfer ofheat by conduction between adjacent tubes when the temperature thereofbecomes alternately cooler and warmer..

This is intended to be represented by the dotted circles surroundingeach tube in Fig. 9.

When it is desired to operate the apparatus so as to dehydrate the airflowing through it the heavier, continuous fins are used to insure theoverlapping of the heat transfer from one tube another. When it isdesired to construct apparatus to condition air by leaving considerablemoisture in it, i. e. with a minimum amount of dehydration, the thin,continuous strips are used. It is evident that the operations, describedare based on the use of continuous fins as distinguished from smallindividual 'fins out of contact with the fins on adjacent. tubes,although under some conditions the latter may be used.

The relationship between the number of square feet of the superficialarea of the evaporator compared to the cubic feet of air handled witheither the thick or the thin fins, is an important feature. This ratioof evaporator area to cubic feet of air handled is approximately two anda quarter to one, or, otherwise expressed, one square foot of evaporatorarea will properly condition two and a half cubic feet of air perminute. If substantially this ratio is obtained, satisfactory operationof the evaporator will take place between temperatures meet any givenrequirements and yet made to handle the number of cubic feet of air forwhich it is designed. The insulated portions of the evaporator may belocated in any practical or convenient place. Although the insulation isshown as applied to the return bends, it is evident' that such insulatedsections may be otherwise located, a's'for example in a path down thecenter of the evaporator; or elsewhere, as the location of theinsulation is not a governing factor as long as it produces portionsisolated from the stream thermal contact with the return line of theorifice and thus compensating for the reduction in the load. It willalso be understood that in a given construction of pipes and fins, thevalve may bev used to regulate the apparatus so that it will operate ator near the dew point without causing the precipitation of moisture, oron the contrary the valve may be adjusted to cause dehydration of theair by precipitating its moisture on the surface of the evaporator.

I claim: V I 1. Air conditioning apparatus comprising a container forthe refrigerant, an evaporator, an,

expansion valve between the two and means for opening said valve atintervals whereby said reopening said valve at short intervals wherebysaid refrigerant is delivered to said evaporator in short impulses, saidmeans being adjustable to vary the frequency and the length of saidintervals.

2. Air conditioning apparatus comprising a container for therefrigerant, an evaporator having a conduit bent back and forth with itsbends thermally insulated and the intermediate spans in heat exchangewith air, an expansion valve between said container and said evaporatorand means for opening said valve at intervals whereby 'said' refrigerantis delivered to said evaporator in impulses, resulting in partial,temporary condensation of said refrigerant in said bends.

3. Air conditioning apparatus comprising a compressor, a condenser, atank, an expansion valve and an evaporator connected to form a closedcircuit, said expansion valve comprising an intermittently actuated timecontrolled valve and a thermostatic valve responsive to the temperatureof the outlet end of said evaporator, to regulate theflow to saidevaporator in accordarice with the load on the latter.

4. In air conditioning equipment comprising a supply tank and anevaporator with a supply pipe and a return pipe, an electro-thermalexpansion valve in said supply pipe, comprising a valve member actuatedat intervals with means to retard its action, .a second valve memberassociated therewith, and a power element associated with said returnline to permit increased flow of refrigerant as the load and hence thetemperature increase.

5. Air conditioning apparatus comprising a container for therefrigerant, an evaporator having a conduit with portions of less heatconductivity than the remainder thereof, an expansion valve between saidcontainer and said evaporator and means for opening said valve atintervals whereby said refrigerant isdelivered to said evaporator inimpulses, resulting in partial temporary condensation of saidrefrigerant in said portions.

6. Air conditioning apparatus comprising a container for therefrigerant, an evaporator having ac'onduit with portions of less heatconductivity than the remainder thereof, an expansion valve between saidcontainer and said evaporator, means for opening said valve at intervalswhereby said refrigerant is delivered to said evaporator in impulses,resulting in partialtemperorary condensation of said refrigerant in saidportions and heat conducting members in contact with said remainingportions and with each other, to equalize temperature differences insaid remaining portions. 7. Air conditioning apparatus comprising acontainer for the refrigerant, an evaporator having a conduit surroundedat intervals by heat insulating material with the intermediate spansexposed, an expansion valve between said container and said evaporatorand means for frigerant is delivered to said evaporator in impulses,resulting in partial, temporary condensation of said refrigerant in saidinsulated portions.

8. Air conditioning apparatus comprising a container for therefrigerant, an evaporator having a conduit surrounded at intervals byheat insulating material with the intermediate spans 1 exposed, anexpansion valve between said container and said evaporator, means foropening 76 said valveat intervals whereby said refrigerant is deliveredto said evaporator in impulses, resulting in partial, temporarycondensation of said refrigerant in said insulatedportions andadditional means controlled by variations in the temperature of theoutlet end of said conduit, for regulating the quantity of refrigerationdelivered to said conduit.

9. The combination with the expansion coil of a mechanical refrigerator,of a source of suppl for the refrigerant, connections therefrom to theinlet end of said coil, a pair of valves arranged in series insaid'connections, temperature responsive means associated with theoutlet end of said expansion coil, power means controlled by saidtemperature responsive means for regulating the flow of refrigerantthrough one of said valves and means for opening and closing the otherof said valves at intervals to deliver said refrigerant'in impulses.

10. The combination with a supply container for refrigerant, anevaporator connected thereto and consisting of a plurality ofsubstantially parallel spaced heat conducting strips having perforationstherein, heat conducting tubes passing through the openings in saidstrips at substantially right angles thereto, parallel side walls havingopenings therein through which the ends of said tubes protrude, meansconnecting the ends of certainadjacent tubes to provide for the flow ofrefrigerant back and forth throughout the series of tubes, heatinsulation surrounding the ends of the tubes outside of said side walls,and means for supplying the refrigerant to said tubes in impulses,whereby alternate tubes are first warmer and then cooler than theremaining tubes, and means for causing the air to be treated to flowover said tubes.

CLARENCE A RODMAN.

